Femtosecond Lasers in Cornea & Refractive Surgery.

Since the introduction of femtosecond laser (FS) systems for corneal flap creation in laser-assisted in-situ keratomileusis there have been numerous applications for FS laser in corneal surgery. This manuscript details the utility of FS lasers in corneal surgical procedures including refractive laser surgeries, intracorneal ring segment tunnels, presbyopic treatments, and FS-assisted keratoplasty. We also review the role of FS lasers in diagnostic procedures such as two photon excitation fluorescence and second harmonic generation.

Depth- and direction-dependent changes in solute transport following cross-linking with riboflavin and UVA light in ex vivo porcine cornea.

Diffusion is an important mechanism of transport for nutrients and drugs throughout the avascular corneal stroma. The purpose of this study was to investigate the depth- and direction-dependent changes in stromal transport properties and their relationship to changes in collagen structure following ultraviolet A (UVA)-riboflavin induced corneal collagen cross-linking (CXL). After cross-linking in ex vivo porcine eyes, fluorescence recovery after photobleaching (FRAP) was performed to measure fluorescein diffusion in the nasal-temporal (NT) and anterior-posterior (AP) directions at corneal depths of 100, 200, and 300 µm. Second harmonic generation (SHG) imaging was also performed at these three corneal depths to quantify fiber alignment. For additional confirmation, an electrical conductivity method was employed to quantify ion permeability in the AP direction in corneal buttons and immunohistochemistry (IHC) was used to image collagen structure. Cross-linked corneas were compared to a control treatment that received the riboflavin solution without UVA light (SHAM). The results of FRAP revealed that fluorescein diffusivity decreased from 23.39 ± 11.60 µm2/s in the SHAM group to 19.87 ± 10.10 µm2/s in the CXL group. This change was dependent on depth and direction: the decrease was more pronounced in the 100 µm depth (P = 0.0005) and AP direction (P = 0.001) when compared to the effect in deeper locations and in the NT direction, respectively. Conductivity experiments confirmed a decrease in solute transport in the AP direction (P < 0.0001). FRAP also detected diffusional anisotropy in the porcine cornea: the fluorescein diffusivity in the NT direction was higher than the diffusivity in the AP direction. This anisotropy was increased following CXL treatment. Both SHG and IHC revealed a qualitative decrease in collagen crimping following CXL. Analysis of SHG images revealed an increase in coherency in the anterior 200 µm of CXL treated corneas when compared to SHAM treated corneas (P < 0.01). In conclusion, CXL results in a decrease in stromal solute transport, and this decrease is concentrated in the most anterior region and AP direction. Solute transport in the porcine cornea is anisotropic, and an increase in anisotropy with CXL may be explained by a decrease in collagen crimping.

Redefining vision assessment.

PURPOSE OF REVIEW: This review outlines ophthalmic diagnostic systems, which objectively evaluates the human visual system and its potential beyond that of Snellen acuity. RECENT FINDINGS: Advances in ophthalmic diagnostic systems have allowed for a deeper understanding of the optical principles of the human eye and have created the opportunity to evolve our current standards of vision assessment beyond Snellen acuity charts. Definitive comparative and validation trials will continue to be necessary in order for these advanced diagnostics to gain more widespread acceptance in the specialty, in addition to providing the guidance on the specific indications and utilities. SUMMARY: Advancements in wavefront analysis, light scatter measurements, and adaptive optics technologies can provide greater insight into an individual optical system's potential and irregularities. Modalities that test for anterior corneal surface and whole eye aberrations, light scatter and contrast sensitivity can be an excellent educational tool for our patients to help them better understand their visual dysfunction and can prove useful for medical or surgical decision-making.

Intraocular lens optics and aberrations.

PURPOSE OF REVIEW: This review outlines concepts in intraocular lens (IOL) optics and aberrations important both for current IOLs and for new IOLs in development. RECENT FINDINGS: Optical aberrations make a significant impact on the laboratory and clinical performance of IOLs, especially under mesopic and low-contrast conditions. Minimizing or correcting these aberrations can potentially improve visual function. Strategic management of aberrations can have clinical utility for extended depth of focus and presbyopia correction. SUMMARY: All IOLs affect ocular aberrations in some manner. It is important for clinicians and researchers to understand the implications how any residual aberrations could affect visual quality, visual side-effects, and depth of focus.

Epithelial and stromal remodeling after corneal collagen cross-linking evaluated by spectral-domain OCT.

PURPOSE: To evaluate changes in corneal epithelial and stromal thickness after corneal collagen cross-linking (CXL) in eyes with keratoconus and postoperative corneal ectasia using spectral-domain optical coherence tomography (SD-OCT). METHODS: Anterior segment SD-OCT (RTVue-100; Optovue, Inc., Fremont, CA) was used to compare regional corneal epithelial and stromal thickness in eyes with keratoconus and ectasia before CXL and 1 and 3 months after CXL. The anterior surface of the cornea, epithelium-Bowman's layer interface, and posterior reflective surface were used as anatomical landmarks to measure epithelial and stromal thickness, respectively. Regional thickness was assessed centrally and at 21 points 0.5 mm apart across the central 6 mm of the corneal vertex in the horizontal and vertical meridians. RESULTS: Thirty-one eyes from 30 patients were evaluated, including 17 eyes (17 patients) with keratoconus and 14 eyes (13 patients) with ectasia. Preoperatively, a highly irregular epithelial thickness profile and distribution was observed in both groups. After CXL, epithelial thickness was significantly thinner 2.5 and 2 mm below and 1.5 mm above the corneal apex (49.26 ± 5.69 µm; range: 43 to 62 µm), and 2.5 and 1 mm nasal and 2 mm temporal to the corneal apex (46.66 ± 4.53 µm; range: 39 to 57 µm) compared to preoperative values (P < .05 for all measurements). Epithelial thickness standard deviations were significantly lower (by 3 to 6 µm) 3 months after CXL, compared to ranges before CXL in both the vertical and horizontal meridians for keratoconus and ectasia (P = .048). No significant differences were found between epithelial remodeling in keratoconus and corneal ectasia (P = .98). No significant or consistent stromal changes were found for either group. CONCLUSIONS: Significant epithelial remodeling occurs after CXL in eyes with keratoconus and corneal ectasia, creating a similar, more regularized thickness profile in all meridians in the early postoperative period. This pattern of remodeling may facilitate interpretation of corneal curvature and thickness changes after CXL and may be related to visual acuity after CXL.

Effects of corneal cross-linking on ocular response analyzer waveform-derived variables in keratoconus and postrefractive surgery ectasia.

PURPOSE: To assess changes in Ocular Response Analyzer (ORA) waveforms after UVA/riboflavin corneal collagen cross-linking (CXL) using investigator-derived and manufacturer-supplied morphometric variables in patients with keratoconus (KC) and postrefractive surgery ectasia. DESIGN: Prospective randomized trial of a standard epithelium-off CXL protocol. PARTICIPANTS: Patients with progressive KC (24 eyes of 21 patients) or postrefractive surgery ectasia (27 eyes of 23 patients) were enrolled. METHODS: Replicate ORA measurements were obtained before and 3 months after CXL. Pretreatment and posttreatment waveform variables were analyzed for differences by paired Student t tests using measurements with the highest waveform scores. MAIN OUTCOME MEASURES: Corneal hysteresis, corneal resistance factor, 37-s generation manufacturer-supplied ORA variables, and 15 investigator-derived ORA variables. RESULTS: No variables were significantly different 3 months after CXL in the KC group, and no manufacturer-supplied variables changed significantly in the postrefractive surgery ectasia group. Four custom variables (ApplanationOnsetTime, P1P2avg, Impulse, and Pmax) increased by small but statistically significant margins after CXL in the postrefractive surgery ectasia group. CONCLUSIONS: Changes in a small subset of investigator-derived variables suggested an increase in corneal bending resistance after CXL. However, the magnitudes of these changes were low and not commensurate with the degree of clinical improvement or prior computational estimates of corneal stiffening in the same cohort over the same period. Available air-puff-derived measures of the corneal deformation response underestimate the biomechanical changes produced by CXL.

Dimensions and anatomic variations of the orbicularis oculi muscle in nonpreserved, fresh-frozen human cadavers.

PURPOSE: To determine average dimensions of the orbicularis oculi muscle (OOM) from the orbital rim and to investigate polymorphic variations through anatomical dissection of nonpreserved, fresh-frozen human cadavers. METHODS: The OOM was exposed using sharp and blunt dissection until its distal borders were identified. A metric ruler was used to measure the superior (S line), inferior (I line), and lateral (L line) dimensions of the OOM from the orbital rim. Data collection included age, gender, and race. Data were analyzed using 2-sample t tests, paired t tests, and mixed effect models. A p-value of ≤0.05 was considered statistically significant. RESULTS: A total of 40 hemifaces of 20 cadavers were dissected. All specimens were Caucasian. Ten specimens were men. Average age was 73.9 years (56-92 years). The overall S line was 1.4 cm (95% confidence interval [CI], 1.23-1.57), the I line was 1.2 cm (95% CI, 1.00-1.36), and the L line was 2.5 cm (95% CI, 2.27-2.68). Men had significantly larger average T, L, and S line values than women (p = 0.003, 0.005, 0.008, respectively). I lines did not differ significantly between genders (p = 0.28). CONCLUSIONS: In senescent Caucasians, the OOM extends approximately 1.4 cm superior, 1.2 cm inferior, and 2.5 cm lateral to the orbital rim. The muscle extends significantly further superiorly and laterally in Caucasian men than in women. Knowledge of the extent of the OOM should improve the understanding and the treatment of conditions affecting this region.

Effect of monofocal, wavefront-shaped and diffractive trifocal intraocular lenses on scanning-slit automated refraction.

PURPOSE: To compare scanning-slit retinoscopy automated refraction spherical equivalent (ARSE) to subjective manifest refraction spherical equivalent (MRSE) in normal eyes with four different types of intraocular lenses (IOLs). DESIGN: Retrospective cross-sectional study METHODS: 279 pseudophakic eyes that underwent lens extraction at a private center with implantation of either a wavefront shaped IOL (Acrysof® Vivity, DFT015), a nonapodized diffractive trifocal IOL (Acrysof® Panoptix), or a monofocal IOL with negative spherical aberration (Tecnis ZCBOO) or aberration-free (Envista Mx60E). Patients who had an automated refraction measurement with retinoscopy refractometer and aberrometer (NIDEK OPD Scan III, Nidek Technologies) and subjective refraction data 1-2 months postoperatively were included in the study. Main outcome measured was the difference between automated refraction and subjective refraction. RESULTS: Sixty-one eyes implanted with a DFT015 IOL, 78 eyes with a TFNT00 IOL, 40 with a ZCBOO IOL and 100 with a Mx60E IOL were enrolled in this study. Statistically significant myopic results were observed when using ARSE compared to MRSE in the DFT015 (-0.95±0.64, -0.33±0.65, p < .001), TFNT00 (-0.43±0.36, -0.2±0.35, p <.001), ZCBOO (-0.81±0.63, -0.4±0.69, p = .008) and Mx60E (-0.75±0.65, -0.45±0.52; p <0.05) IOL groups. The absolute difference between the 2 methods was statistically significant in the DFT015 IOL group (0.65±0.49; p< 0.05). CONCLUSION: Automated refraction yields myopic results in pseudophakic eyes with monofocal and presbyopia correcting IOLs and may be used with caution. Manifest refraction "push-plus" technique should be used in all pseudophakic eyes to avoid over-minus prescriptions, especially in patient with residual refractive error following cataract surgery.

Prediction of the small aperture intraocular lens on visual acuity in patients with keratoconus.

PURPOSE: To investigate the impact of corneal higher-order aberrations (HOAs) on predicted corrected distance visual acuity (CDVA) in patients with keratoconus at varying simulated pupil apertures. SETTING: Ophthalmology Clinics, Medical University of South Carolina, Charleston, South Carolina. DESIGN: Retrospective chart review study. METHODS: 56 eyes with keratoconus were examined using Scheimpflug tomography during routine examinations before medical intervention. The severity of keratoconus was graded using the Amsler-Krumeich classification. Zernike analysis was used to obtain corneal aberrations using simulated pupil diameters of 6 mm, 4 mm, and 2 mm. These data were extrapolated to obtain the total root mean square HOAs for a 1.6 mm simulated pupil to evaluate the potential effect of a small aperture intraocular lens (IOL). Correlation analysis was used to study the impact and relative contributions of HOAs on CDVA. Convolution of HOAs from OPD-Scan III provided a clinical method to predict CDVA with different simulated pupil sizes in corneas with irregular astigmatism. RESULTS: There were statistically significant positive correlations between photopic CDVA and the magnitude of total and individual (coma, spherical aberration, and trefoil) HOAs in this cohort of keratoconus participants. A keratoconus case with the small aperture IOL confirms the improvement in vision due to the pinhole effect. CONCLUSIONS: The small aperture IOL is expected to markedly reduce aberrations in patients with keratoconus up to Amsler-Krumeich class 4 severity to levels consistent with the levels seen in healthy patients. Convolution of corneal HOAs with the Early Treatment Diabetic Retinopathy Study chart provides a useful simulation of the impact of pinhole optics in aberrated eyes.

Current state and future perspectives in the diagnosis of eyelid margin disease: clinical review.

The eyelid margin is vital to ocular surface integrity. Much peer-reviewed literature has been established in eyelid margin inflammation, better known as blepharitis. The purpose was to review and understand the impact of eyelid margin disease. Anterior blepharitis causes inflammation at the eyelash base, ciliary follicles, and the palpebral skin. Posterior blepharitis occurs when there is inflammation with the posterior eyelid margin disease. In common usage, the term "blepharitis" used alone almost always refers to anterior blepharitis. Classification of eyelid margin disease should be based on etiopathogenesis, location, primary vs secondary, and chronicity. Blepharitis has several etiopathologies (infectious, inflammatory, and squamous). Meibomian gland dysfunction (MGD) can refer to the functional and/or structural problems with the meibomian gland. Meibomitis (or meibomianitis) occurs when there is inflammation associated with the MGD. The presence of blepharitis and/or MGD (with or without inflammation) can affect the ocular surface and thereby affect anterior segment and cataract surgeries. This review article evaluates the differential diagnoses of eyelid margin disease, including various forms of blepharitis, MGD, and meibomitis.

Eyelid margin disease (blepharitis and meibomian gland dysfunction): clinical review of evidence-based and emerging treatments.

Blepharitis is a common ophthalmic condition with multiple etiologies and no definitive, universal treatment. The treatment modalities for managing lid margin diseases vary depending on the disease's cause, location, and severity. For anterior blepharitis, management options include eyelid hygiene with warm compresses, eyelid scrubs, baby shampoo, and over-the-counter eyelid cleansers. Topical antibiotics and antibiotic-steroid combination drops/ointments for the eye and eyelid may accompany these. For posterior blepharitis/meibomian gland dysfunction (MGD), at-home warm compress or in-office administration of heat therapy/thermal pulsation treatment that aims to clear obstruction in the meibomian glands and restore meibum secretions to maintain a healthy tear film is recommended. In addition to the above treatment strategies, various other compounds to manage lid margin diseases are in the late stages of development. This review summarizes the available treatment modalities or those in the pipeline for treating blepharitis and MGD.

SD-OCT analysis of regional epithelial thickness profiles in keratoconus, postoperative corneal ectasia, and normal eyes.

PURPOSE: To assess corneal microarchitecture and regional epithelial thickness profile in eyes with keratoconus, postoperative corneal ectasia (ectasia), and normal unoperated eyes (controls) using spectral-domain optical coherence tomography (SD-OCT). METHODS: Regional corneal epithelial thickness profiles were measured with anterior segment SD-OCT (Optovue RTVue-100, Optovue Inc., Fremont, CA). Epithelial thickness was assessed at 21 points, 0.5 mm apart, across the central 6-mm of the corneal apex in the horizontal and vertical meridians. RESULTS: One hundred twenty eyes were evaluated, including 49 eyes from 29 patients with keratoconus, 32 eyes from 16 patients with ectasia, and 39 eyes from 21 control patients. Average epithelial thickness at the corneal apex was 41.18 ± 6.47 µm (range: 30 to 51 µm) for keratoconus, 46.5 ± 6.72 µm for ectasia (range: 34 to 60 µm), and 50.45 ± 3.92 µm for controls (range: 42 to 55 µm). Apical epithelial thickness was significantly thinner in eyes with keratoconus (P < .0001) and ectasia (P = .0007) than in controls. Epithelial thickness ranges in all other areas varied widely for keratoconus (range: 21 to 101 µm) and ectasia (range: 30 to 82 µm) compared to controls (range: 43 to 64) (P = .0063). CONCLUSION: SD-OCT demonstrated significant central and regional epithelial thickness profile differences between keratoconus, ectasia, and control eyes, with significant variability and unpredictability in ectatic eyes. This regional irregularity may necessitate direct epithelial thickness measurement for treatments where underlying stromal variations may be clinically relevant, including corneal collagen cross-linking or topography-guided ablations.

Tolerance to Induced Astigmatism With a Monofocal Intraocular Lens Designed to Extend the Depth of Focus.

PURPOSE: To determine tolerance to residual astigmatism and visual performance in eyes implanted with a monofocal intraocular lens (IOL) designed to extend the depth of focus (Tecnis Eyhance, DIB00; Johnson & Johnson Vision) compared to eyes implanted with a standard monofocal IOL (Tecnis ZCB00; Johnson & Johnson Vision). METHODS: This prospective, observational study enrolled consecutive patients who underwent routine cataract surgery and implantation of either the DIB00 (n = 20) or ZCB00 (n = 20) IOL. Astigmatic defocus was induced with a plus cylinder from +0.50 to +2.00 diopters (D) in 0.50-D steps for each astigmatic orientation (against-the-rule [ATR], with-the-rule [WTR], and oblique). Outcome measures included the comparison of mean visual acuity at each step of defocus, astigmatic defocus curves, and near and intermediate visual acuity. RESULTS: Eyes implanted with the DIB00 demonstrated greater astigmatic tolerance and were more likely to maintain 20/40 or better visual acuity with up to +2.00 D of induced ATR and oblique astigmatism than the ZCB00 IOLs. The DIB00 group showed 1.3 lines better visual acuity at 2.00 D of ATR astigmatic defocus and 1 line better than the ZCB00 group at 1.50 D of oblique astigmatic defocus. Although the distance visual acuity was comparable, near and intermediate visual acuities (both distance-corrected and uncorrected) were better for the DIB00 IOL than for the standard ZCB00 IOL. CONCLUSIONS: The monofocal IOL designed to extend the depth of focus (DIB00 group) showed greater tolerance to induced astigmatism in ATR and oblique orientations and superior uncorrected and distance-corrected near and intermediate visual acuity than the standard monofocal IOL of the same IOL platform. [J Refract Surg. 2023;39(4):222-228.].

Spectral-Domain OCT Lens Meridian Position as a Metric to Estimate Postoperative Anatomical Lens Position.

PURPOSE: To evaluate the prediction of postoperative anatomical lens position (ALP) using intraoperative spectral-domain optical coherence tomography (SD-OCT) lens anatomy metrics in patients who underwent femtosecond laser-assisted cataract surgery. METHODS: Intraoperative SD-OCT (Catalys; Johnson & Johnson Vision) and postoperative optical biometry (IOLMaster 700; Carl Zeiss Meditec AG) were used to assess anterior segment landmarks, including lens thickness, lens volume, anterior chamber depth, lens meridian position (LMP), and measured ALP. LMP was defined as the distance from the corneal epithelium to the lens equator, and ALP was defined as the distance from the corneal epithelium to the IOL surface. Eyes were divided into groups according to axial length (> 22.5 mm, 22.5 to 24.5 mm, and > 24.5 mm) and IOL type (Tecnis ZCB00 [Johnson & Johnson Vision]; AcrySof SN-60WF [Alcon Laboratories, Inc], or enVista MX60E [Bausch & Lomb]) to further analyze the correlation between LMP and ALP. Theoretical effective lens position was back-calculated using a specific formula. Primary outcome was correlation between postoperative measured ALP and LMP. RESULTS: A total of 97 eyes were included in this study. Linear regression analysis displayed a statistically significant correlation between intraoperative LMP and postoperative ALP (R2 = 0.522; P < .01). No statistically significant correlation was observed between LMP and lens thickness (R2 = 0.039; P = .06) or between ALP and lens thickness (R2 = 0.02; P = .992). The greatest predictor for ALP was LMP (ß = 0.766, P < .001; R2 = 0.523). CONCLUSIONS: Intraoperative SD-OCT-measured LMP correlated better than anterior chamber depth and axial length to postoperative ALP. Further studies are necessary to analyze the impact of preoperative or intraoperative LMP measurements on postoperative refractive outcomes. [J Refract Surg. 2023;39(3):165-170.].

Optimized Artificial Intelligence for Enhanced Ectasia Detection Using Scheimpflug-Based Corneal Tomography and Biomechanical Data.

PURPOSE: To optimize artificial intelligence (AI) algorithms to integrate Scheimpflug-based corneal tomography and biomechanics to enhance ectasia detection. DESIGN: Multicenter cross-sectional case-control retrospective study. METHODS: A total of 3886 unoperated eyes from 3412 patients had Pentacam and Corvis ST (Oculus Optikgeräte GmbH) examinations. The database included 1 eye randomly selected from 1680 normal patients (N) and from 1181 "bilateral" keratoconus (KC) patients, along with 551 normal topography eyes from patients with very asymmetric ectasia (VAE-NT), and their 474 unoperated ectatic (VAE-E) eyes. The current TBIv1 (tomographic-biomechanical index) was tested, and an optimized AI algorithm was developed for augmenting accuracy. RESULTS: The area under the receiver operating characteristic curve (AUC) of the TBIv1 for discriminating clinical ectasia (KC and VAE-E) was 0.999 (98.5% sensitivity; 98.6% specificity [cutoff: 0.5]), and for VAE-NT, 0.899 (76% sensitivity; 89.1% specificity [cutoff: 0.29]). A novel random forest algorithm (TBIv2), developed with 18 features in 156 trees using 10-fold cross-validation, had a significantly higher AUC (0.945; DeLong, P < .0001) for detecting VAE-NT (84.4% sensitivity and 90.1% specificity; cutoff: 0.43; DeLong, P < .0001) and a similar AUC for clinical ectasia (0.999; DeLong, P = .818; 98.7% sensitivity; 99.2% specificity [cutoff: 0.8]). Considering all cases, the TBIv2 had a higher AUC (0.985) than TBIv1 (0.974; DeLong, P < .0001). CONCLUSIONS: AI optimization to integrate Scheimpflug-based corneal tomography and biomechanical assessments augments accuracy for ectasia detection, characterizing ectasia susceptibility in the diverse VAE-NT group. Some patients with VAE may have true unilateral ectasia. Machine learning considering additional data, including epithelial thickness or other parameters from multimodal refractive imaging, will continuously enhance accuracy. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Ray-tracing Analysis of Accommodation and Pseudoaccommodation in Phakic and Pseudophakic Eyes.

PURPOSE: To compare objective measurements of accommodation and pseudoaccommodation in phakic and pseudo-phakic eyes using ray-tracing aberrometry. METHODS: Patients with normal and hyperprolate corneas (post-hyperopic laser in situ keratomileusis) who underwent cataract surgery from March 2018 to October 2019 at the Medical University of South Carolina were examined and received either a diffractive intraocular lens (IOL) with an echelette design (Tecnis ZXR00 Symfony; Johnson & Johnson Vision), a monofocal IOL with negative spherical aberration (Tecnis ZCB00; Johnson & Johnson Vision), or an aberration-free IOL (MX60E; Bausch & Lomb). The control groups consisted of young and presbyopic phakic patients. Ray-tracing wavefront analysis was performed 1 to 3 months postoperatively. Objective ray-tracing metrics of accommodation and pseudoaccommodation included the effective range of focus, sphere shift accommodation, and depth of focus. RESULTS: Sixty-two eyes received a Tecnis ZCB00, 39 a MX60E, and 43 a Tecnic ZXR00 Symfony IOL; furthermore, 20 young phakic eyes and 19 presbyopic eyes were included in this study. The effective range of focus and sphere shift accommodation in the young control group were statistically larger than in the presbyopic group (P = .005 and P < .001, respectively). There was no difference in effective range of focus, sphere shift accommodation, and pseudoaccommodations between the different IOL groups. The young control group had the highest visual Strehl optical transfer function for near and distant targets (0.64 ± 0.24 and 0.56 ± 0.19, respectively), whereas the aberration-free IOL in the MX60E hyperprolate cornea group presented the lowest visual Strehl optical transfer function value for near (0.49 ± 0.19). CONCLUSIONS: Ray-tracing aberrometry can objectively assess accommodative amplitude in phakic eyes and pseudoaccommodation (depth of focus) in pseudophakic eyes. [J Refract Surg. 2022;38(10):661-667.].

Scheimpflug-Derived Corneal Lower and Higher Order Aberrations Post Intrastromal Corneal Ring Segments for Keratoconus.

Intrastromal corneal ring segments (ICRS) improve corneal topographic symmetry and reduce corneal aberrations through regularization of the corneal surface, thereby functioning as a viable surgical intervention for patients with keratoconus. This study aims to evaluate changes in lower- (LOAs) and higher-order aberrations (HOAs) amongst varying pupil sizes pre- and post- ICRS implantation in keratoconus patients. We specifically investigate the impact of pupil size on total corneal HOAs up to the 6th order. Twenty-one eyes that underwent ICRS implantation were included in this prospective interventional study. LOAs and HOAs measurements at the 6 mm, 4 mm, and 2 mm pupil diameters were collected preoperatively and at 6 months postoperatively using the Zernicke analysis function on a Scheimpflug device. ICRS implantation demonstrated a statistically significant effect in vertical coma with a −0.23 reduction (p = 0.015) for a 4 mm pupil size and a −1.384 reduction (p < 0.001) for 6 mm, with no significant effect at 2 mm. Horizontal coma, astigmatism 0°, astigmatism 45°, trefoil 5th order 30°, and RMS HOA demonstrated significant reductions at 4 mm or 6 mm pupil sizes but not at 2 mm. Our analysis demonstrates a favorable effect of ICRS implantation on larger pupil sizes, suggesting the importance of pupil size as it correlates with HOAs reduction.

Anterior segment reconstruction due to cosmetic iris implants placed in the anterior chamber.

A 27-year-old woman had BrightOcular iris implants placed for cosmetic purposes that changed eye color from brown to blue bilaterally. Of note, BrightOcular implants are not approved by the U.S. Food and Drug Administration (FDA) for use in the United States and have been associated with severe ocular complications. In keeping with their design, they were placed in the anterior chamber (AC) in both eyes of this patient; surgery was performed outside the United States. As has been described previously and tragically in other cases, she developed chronic inflammation, intolerable glare, angle-closure glaucoma, corneal edema, and cataracts in both eyes. For medically unmanageable elevated intraocular pressure (IOP), she underwent diode laser cyclophotocoagulation (CPC) in both eyes, and eventually, an Ahmed tube shunt (New World Medical, Inc.) was placed in the right eye. Although she was advised and urged to have the iris implants removed, despite her ocular issues, she refused removal until intolerable glare and reduced vision ensued. Ultimately, both iris implants were extracted 5 years after implantation by a U.S. surgeon; the procedures resulted in corneal decompensation and progressive cataract development. Subsequent penetrating keratoplasty (PKP) was performed for the right eye, but it failed because of contact with the glaucoma tube shunt. She sought additional consultation and presented with the following findings: corrected distance visual acuity was 20/400 in the right eye and 20/40 in the left eye, IOP of 18 mm Hg in the right eye and 16 mm Hg in the left eye, pupils were nonreactive and fixed, and extraocular muscles and central visual field were normal. Pachymetry was 868 µm in the right eye and 653 µm in the left eye. Anterior segment examination in the right eye revealed a failed corneal graft with 3+ edema, peripheral anterior synechiae (PAS) for 360 degrees, shallow AC, Ahmed tube shunt at the 11 o'clock position and remnant iris adherent to the graft-host junction for 270 degrees, 3+ posterior subcapsular cataract, and 2+ cortical cataract (Figure 1JOURNAL/jcrs/04.03/02158034-202208000-00024/figure1/v/2022-08-01T210317Z/r/image-tiff). The sclera revealed multiple circular and circumferential atrophic blue spots consistent with high-energy transscleral CPC (Figure 2JOURNAL/jcrs/04.03/02158034-202208000-00024/figure2/v/2022-08-01T210317Z/r/image-tiff). In the left eye, she had remnant fixed dilated iris for 270 degrees, missing iris superiorly for 3 clock hours, an adequate AC, and 2+ cortical cataract (Figure 3JOURNAL/jcrs/04.03/02158034-202208000-00024/figure3/v/2022-08-01T210317Z/r/image-tiff). Posterior segment examination revealed a 0.5 cup-to-disc ratio in both eyes with normal vessels, macula, vitreous, and retinal periphery, bilaterally. Given this constellation of findings, how would you proceed?

Analysis of microkeratome thin flap architecture using Fourier-domain optical coherence tomography.

PURPOSE: To assess the corneal architecture and reproducibility of LASIK flap thickness created by the Amadeus II mechanical microkeratome (Ziemer Ophthalmic Systems AG) using Fourier-domain optical coherence tomography (OCT; Optovue Inc). METHODS: Anterior segment Fourier-domain OCT was used to analyze the morphology of 58 LASIK flaps from 30 patients created with the Amadeus II microkeratome 140-µm head and ML7090CLB blades (Med-Logics Inc) at 2 weeks postoperatively. Flap thickness was assessed at 10 points across the central 6 mm of the cornea (horizontal and vertical meridians). Postoperative central corneal flap thickness measured by Fourier-domain OCT was compared with intraoperative ultrasound pachymetry measurements. RESULTS: No significant difference was noted between central flap thickness measured by intraoperative pachymetry (107.2 ± 14 µm) and postoperative OCT (111.7 ± 11 µm; P=.07, correlation coefficient=0.86). Fourier-domain OCT measurements demonstrated functionally planar flap architecture (standard deviation [SD] of thickness across the flap=4.9 µm, SD range across the flap=2 to 9 µm) for the microkeratome flaps. CONCLUSIONS: The Amadeus II microkeratome with Med-Logics blades created thin, reproducible, functionally planar flaps as measured by Fourier-domain OCT. Central flap thickness measured by intraoperative ultrasound pachymetry was equivalent to that measured 2 weeks postoperatively by OCT.

Comparison of optical aberrations and contrast sensitivity between aspheric and spherical intraocular lenses.

PURPOSE: To compare visual acuity, aberrometry, and contrast sensitivity in patients who had a spherical intraocular lens (IOL) (SoFlex SE, Bausch & Lomb) implanted in one eye and an aspheric IOL (SofPort AO, Bausch & Lomb) implanted in the fellow eye during uncomplicated cataract surgery. METHODS: A prospective, multicenter, double-blind study was performed. Forty patients (80 eyes) underwent bilateral phacoemulsification with implantation of a spherical IOL in one eye and an aspheric IOL in the fellow eye. Postoperatively, visual acuity, aberrometry, and contrast sensitivity tests were performed. Statistical analyses were performed using Student t and Wilcoxon tests, and mixed effects were used for each contrast condition situation. RESULTS: Thirty-nine patients (30 women, 9 men; 78 eyes) with a mean age of 69.3±6.17 years (range: 51 to 82 years) completed the study. No statistical differences were found regarding visual acuity among eyes. Lower levels of higher order aberrations were achieved in the aspheric group. No statistical difference between groups under photopic conditions was noted. In low spatial frequencies, better performance was observed with the aspheric IOL under mesopic conditions. In high spatial frequencies, the spherical IOL produced better quality of vision. Comparing mesopic conditions with glare, visual performance was statistically better using the aspheric IOL. CONCLUSIONS: Cataract surgery results cannot be measured by means of visual acuity alone. Quality of vision must be considered, and implantation of IOLs with low levels of spherical aberrations and better contrast sensitivity are preferred. In this study, the aspheric IOL demonstrated better visual function, especially at night, when compared with spherical IOLs.